Bash string manipulation without a variable

Question

In Bash, it is possible to do string manipulation on a variable, for example to get the current runlevel on a Linux machine:

current_runlevel=$(runlevel) #sample output: 'N 2'
current_runlevel=${current_runlevel#* }
echo $current_runlevel #sample output: '2'

However, is it possible to combine the two lines, so no intermediate variable is required? Using the same example, I want it to look something like:

current_runlevel=${$(runlevel)#* }

This does not work, giving the error

${$(runlevel)#* }: bad substitution

Any ideas on how it might be possible to use a literal string in Bash string manipulation expressions?

@Bill Please don't use "pls." And I don't see how that question is relevant anyway. — Kevin
– Kevin, Commented Jun 28, 2013 at 13:10

user80168 · Accepted Answer · 2013-06-28 12:58:23Z

5

Well, not really. You can, though use sed, or something similar, like:

current_runlevel=$( runlevel | cut -d' ' -f2 )

Using intermediary variable will be a bit faster though.

answered Jun 28, 2013 at 12:58

user80168

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1 Comment

I would much prefer using an intermediate variable than creating a new process. It is neater, though.